This paper proposes a new and simple algorithm for face extraction from a color image. The approach detects the lip region in a face object. First, the lip- and skin-color pixels in an image are extracted on the basis of statistical probability analysis. These lip- and skin-color pixels are segmented separately by using binary image processing techniques to produce lip- and skin-color regions. Each region that has a skin-color region and one or more lip-color regions as its subset regions is nominated as a face candidate. To detect only the face objects from the face candidates, the algorithm evaluates the values of seven pattern variables of those face candidates. A face candidate with all its seven pattern variable values within the valid range values of face object class is detected as a face object. Verifications of the proposed algorithm were provided by the experimental results that gave 91.8% detection of face objects from 104 sample images. This is significant for locating or detecting the faces in color images.
Demas Sanger, Yoichi Miyake, Hideaki Haneishi, Norimichi Tsumura, "Algorithm for Face Extraction Based on Lip Detection" in Journal of Imaging Science and Technology, 1997, pp 71 - 80, https://doi.org/10.2352/J.ImagingSci.Technol.1997.41.1.art00011